Systems Analysis and Design Computing Essentials 1999 - 2000 Systems Analysis and Design

Computing Essentials 1999 - 2000 Overview Effective information systems don’t happen by accident, they are the result of considerable thought and effort A six step problem-solving process called systems analysis and design underpins the development of effective information systems Computing Essentials 1999 - 2000 Systems Analysis and Design

System Analysis and Design System - “collection of activities and elements organized to accomplish a goal” Information system - “collection of hardware, software, people, procedures and data” Computing Essentials 1999 - 2000 Systems Analysis and Design

The Traditional Systems Development Life Cycle (SDLC) The SDLC is a structured framework that consists of sequential processes by which information systems are developed. Computing Essentials 1999 - 2000

System Analysis and Design Steps Preliminary investigation – overview of problems and solutions, feasibility considered, report prepared Systems analysis - system studied, new requirements specified Systems design - new or alternative system design to solve problem Computing Essentials 1999 - 2000 Systems Analysis and Design

System Analysis and Design Steps Systems development - new hardware and software acquired, developed and system tested (not live) Systems implementation – conversion to new live system with training Systems maintenance - periodic evaluation and updating Computing Essentials 1999 - 2000 Systems Analysis and Design

Systems Analysis and Design Computing Essentials 1999 - 2000 Systems Analysis and Design

Phase 1: Preliminary Investigation In the preliminary investigation phase, the problems are briefly identified and a few solutions are suggested Computing Essentials 1999 - 2000

Phase 1: Preliminary Investigation To determine if a new system is needed, problems are briefly identified and a few solutions are suggested Systems analysts here are concerned with three tasks: Briefly defining the problem Suggesting alternative solutions Preparing a short report Computing Essentials 1999 - 2000

Phase 1: Preliminary Investigation Defining the problem Examining current system By observation and interview, determining what information is needed by whom, when, where and why Suggesting alternative systems Short report summarizing investigation results Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Phase 1: Preliminary Investigation Alternative systems are designed and evaluated for Economic feasibility - do benefits justify costs? Technical feasibility - is reliable technology and training available? Operational feasibility - will the employees, managers or clients support it? Time feasibility – can the project be competed within a suitable time frame? Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Phase 2: Analysis In the systems analysis phase, the present system is studied in depth, and new requirements are specified. Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Gathering Data Expanding on data gathered in Phase 1 In addition to observation and interviews, formal lines of authority and standard operating procedures investigated Organization chart excellent source document during this phase Computing Essentials 1999 - 2000

Organisation chart and management pyramid CEO VP Accounting VP Marketing VP Production VP HR VP Research … etc Workers Supervisors Control Middle Manager Control & Planning Top Managers Long-Range Planning Organisation chart and management pyramid Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Analyzing the Data How information flows, and reasons for any inefficiencies Checklists - list of questions Top-down analysis methodology - start with top level components, break down through each successive level Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Analyzing the Data Grid charts - to show relationship between inputs and outputs System flowcharts - charts flow of input data to processing and finally to output Data flow diagrams - displays data or information flow within an information system Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 System Flowchart Computing Essentials 1999 - 2000

System Flowchart Symbols decision Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Analyzing the Data Automated design tools Help systems analyst evaluate hardware and software alternatives Often called computer-aided software engineering tools or CASE tools Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Client Database Client Information Update if necessary Request Service Client Request Accepted Completed Service Time & Billing Database Verify Account Perform Service Request Denied Bill Mailed Prepare Client Bill Database Updated Data Flow Diagram Data Flow Diagram (DFD) Symbols Computing Essentials 1999 - 2000 Data Flow Entity Process File

Documenting the Systems Analysis Stage In report to higher management Current system described Requirements for new system specified Possible development schedule proposed Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Phase 3: Design Systems analysis describes what a system must do to solve the business problem, and systems design describes how the system will accomplish this task Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Phase 3: Design In selecting the best system, questions that must be answered: Will new system fit into overall system? Will it be flexible for the future? Can it be secured against unauthorized use? Are the costs worth the benefits? Writing the systems design report - alternatives described, one recommended Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 The deliverable of the systems design phase is the technical design -- that specifies the following: System outputs, inputs, and user interfaces Hardware, software, databases, telecommunications, personnel, and procedures How these components are integrated Computing Essentials 1999 - 2000

Two Major Aspects of the New System Logical systems design States what the system will do Physical systems design States how the system will perform its functions Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Phase 4: Development In the systems development phase, new hardware and software are developed, acquired and tested. Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Phase 4: Development Developing software - two options Off-the-shelf Custom designed Acquiring hardware - what kinds needed and where to install Testing the new system Sample data fed into system Results evaluated Computing Essentials 1999 - 2000

Phase 5: Implementation In the systems implementation phase, the new information system is installed, and people are trained to use it. Computing Essentials 1999 - 2000

Phase 5: Implementation Types of conversion Direct approach - old system abandoned, new one adopted Parallel approach - both systems operated side by side until new system proves itself Computing Essentials 1999 - 2000

Phase 5: Implementation Types of conversion (cont.) Pilot approach - new system launched in only one area of the business, once system operating smoothly implementation goes company-wide Phased approach - gradual implementation over time Computing Essentials 1999 - 2000

Phase 5: Implementation Pilot and phased approach most favored Training Most commonly overlooked Can be commenced before equipment delivery Outside trainers sometimes used Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Phase 6: Maintenance Systems maintenance is first a systems audit and then an ongoing evaluation to see whether a system is performing productively. Computing Essentials 1999 - 2000

Computing Essentials 1999 - 2000 Phase 6: Maintenance Systems audit - performance compared to original specifications Periodic evaluation - “checkups” from time to time, modifications if necessary Computing Essentials 1999 - 2000